Suddenly turns off and immediately shuts down after turning on.

[Reyu]

Yesterday, I booted my pc, after a while of browsing, it turned off suddenly and I immediately turned it on again. The lights were on, the fans were spinning everything seemed to be in order however, after a second of starting up it died and it happened every single time I tried. I started to troubleshoot my pc first in order for me to try and deduce as to which hardware might be at fault, I cleaned the pins for both my gpu and RAMS, unplug and plug the psu cables ensuring them that they are connected, reset CMOS. After doing all these, my pc was able to boot to desktop, however, it died again, and the cycle begin where I am not able to boot normally as it kept on dying after turning on for a few seconds. Take note that there are no overheating errors. I hypothesized that this might have something to do with either the RAMS, PSU, or Motherboard. First, I tried removing each ram trying out different slots, and I've noticed that when I use only on RAM, I am able to boot into desktop and won't crash as frequently, however, this is not the case when I use two RAMS at the same time. Also, the RAM must also be seated at a specific slot before it works. I'm really at my wits end here, I need your help in deducing if this has to do with the motherboard itself or the PSU, or something else. (and sorry for the grammar or there might be words/phrases that can be ambiguous, I'm typing so fast in case my desktop dies on me again :<)